英語(yǔ)時(shí)差：迷人的單細(xì)胞生物（上）

When we think about the evolution of life on our planet, we usually think of minuscule single-celled organisms as the simple precursors to more complex, multi-cellular life forms. You might remember seeing single-cell organisms under a microscope in biology class, and perhaps you remember them as rather boring blobs. Life got much more interesting and complex when the cells joined together to become animals or plants. Most people–biologists as well as you and I–think of cells primarily as building blocks of more complicated organisms. That’s why an organism called “Caulerpa,” a kind of alga, is so fascinating. There are over seventy different species of Caulerpa, which grow in warm, shallow lagoons around the world.